1. Field of the Invention
The present invention relates generally to a method and apparatus for forming blow molded plastic containers. More particularly, the present invention relates to a method and apparatus that utilizes a movable, in-mold structure for displacing a portion of the blow molded container, such as the base.
2. Related Art
Conventionally, a container may be manufactured through a process known as blow molding. In blow molding, a parison is received at a blow molding apparatus, and the parison is enclosed by a container mold. The blow molding apparatus inflates the parison by forcing gas into the parison which causes the parison to stretch and take the shape of the container mold. Once the parison has taken the shape of the container mold, the blow molding step is complete and the container is removed from the container mold for further processing.
In some applications of container manufacturing, a deep protrusion may be required at a particular section of a container, for example, at a base or at a hand grip of the container. Deep protrusions, when located at the base of the container, are sometimes referred to as “push-ups” since the protrusions push up into the interior of the container. Employing known techniques to manufacture containers with deep protrusions has various problems. One such problem is the lack of orientation of the plastic material around the deep protrusion, as discussed in more detail in co-pending U.S. Patent Application No. 60/671,459, the entire content of which is incorporated herein by reference.
There remains a need in the art, however, for an apparatus and method for forming blow molded plastic containers that include a deep protrusion or other structure extending into the interior of the container.